How effective is harassment on infalling late-type dwarfs?

A new harassment model is presented that models the complex, and dynamical tidal field of a Virgo like galaxy cluster. The model is applied to small, late-type dwarf disc galaxies (of substantially lower mass than in previous harassment simulations) as they infall into the cluster from the outskirts. These dwarf galaxies are only mildly affected by high speed tidal encounters with little or no observable consequences; typical stellar losses are $<10\%$, producing very low surface brightness streams ($\mu_B > 31$ mag arcsec$^{-2}$), and a factor of two drop in dynamical mass-to-light ratio. Final stellar discs remain disc-like, and dominated by rotation although often with tidally induced spiral structure. By means of Monte-Carlo simulations, the statistically likely influences of harassment on infalling dwarf galaxies are determined. The effects of harassment are found to be highly dependent on the orbit of the galaxy within the cluster, such that newly accreted dwarf galaxies typically suffer only mild harassment. Strong tidal encounters, that can morphologically transform discs into spheroidals, are rare occurring in $<15 \%$ of dwarf galaxy infalls for typical orbits of sub-structure within $\Lambda$CDM cluster mass halos. For orbits with small apocentric distances ($<$250 kpc), harassment is significantly stronger resulting in complete disruption or heavy mass loss ($>90 \%$ dark matter and $> 50 \%$ stellar), however, such orbits are expected to be highly improbable for newly infalling galaxies due to the deep potential well of the cluster.Comment: 15 pages, 11 figures, 4 table

Comparison of Wechsler Memory Scale–Fourth Edition (WMS–IV) and Third Edition (WMS–III) dimensional structures: Improved ability to evaluate auditory and visual constructs

Dimensional structures underlying the Wechsler Memory Scale–Fourth Edition (WMS–IV) and Wechsler Memory Scale–Third Edition (WMS–III) were compared to determine whether the revised measure has a more coherent and clinically relevant factor structure. Principal component analyses were conducted in normative samples reported in the respective technical manuals. Empirically supported procedures guided retention of dimensions. An invariant two-dimensional WMS–IV structure reflecting constructs of auditory learning/memory and visual attention/memory (C1 = .97; C2 = .96) is more theoretically coherent than the replicable, heterogeneous WMS–III dimension (C1 = .97). This research suggests that the WMS–IV may have greater utility in identifying lateralized memory dysfunction

CRATE: A Simple Model for Self-Describing Web Resources

If not for the Internet Archive’s efforts to store periodic snapshots of the web, many sites would not have any preservation prospects at all. The barrier to entry is too high for everyday web sites, which may have skilled webmasters managing them, but which lack skilled archivists to preserve them. Digital preservation is not easy. One problem is the complexity of preservation models, which have specific meta-data and structural requirements. Another problem is the time and effort it takes to properly prepare digital resources for preservation in the chosen model. In this paper, we propose a simple preservation model called a CRATE, a complex-object consisting of undifferentiated metadata and the resource byte stream. We describe the CRATE complex object and compare it with other complex-object models. Our target is the everyday, personal, departmental, or community web site where a long-term preservation strategy does not yet exist

Creating Preservation-Ready Web Resources

There are innumerable departmental, community, and personal web sites worthy of long-term preservation but proportionally fewer archivists available to properly prepare and process such sites. We propose a simple model for such everyday web sites which takes advantage of the web server itself to help prepare the site\u27s resources for preservation. This is accomplished by having metadata utilities analyze the resource at the time of dissemination. The web server responds to the archiving repository crawler by sending both the resource and the just-in-time generated metadata as a straight-forward XML-formatted response. We call this complex object (resource + metadata) a CRATE. In this paper we discuss modoai, the web server module we developed to support this approach, and we describe the process of harvesting preservation- ready resources using this technique

EFFECTS OF INCREASED VELOCITY ON THE KINEMATICS OF Vl SKATING IN CROSS COUNTRY SKIl G

The ''VI'' or "alternate stride" skate has become the predominant skating method used in the cross country "free" technique races. The evolution of cross country skiing has developed away from the traditional techniques such as diagonal stride which require machine set tracks and toward faster skating techniques requiring only a packed surface. The tecbniql1es resemble ice skating strides in some respects and are generically labeled "skating." Several variations of skating technique are used in racing. V2 skating involves a poling thrust (both poles simultaneously) with the skating motion on each side

Tools for a Preservation-Ready Web

PDF of a powerpoint presentation from the National Digital Information Infrastructure and Preservation Program (NDIIPP) Partners Meeting, Washington D.C., July 9, 2008. Also available on Slideshare.https://digitalcommons.odu.edu/computerscience_presentations/1027/thumbnail.jp